Abstract

Many organisms and tissues display the ability to heal and regenerate as needed for normal physiology and as a result of pathogenesis. However, these repair activities can also be observed at the single-cell level. The physical and molecular mechanisms by which a cell can heal membrane ruptures and rebuild damaged or missing cellular structures remain poorly understood. This Review presents current understanding in wound healing and regeneration as two distinct aspects of cellular self-repair by examining a few model organisms that have displayed robust repair capacity, including Xenopus oocytes, Chlamydomonas, and Stentor coeruleus Although many open questions remain, elucidating how cells repair themselves is important for our mechanistic understanding of cell biology. It also holds the potential for new applications and therapeutic approaches for treating human disease.

Figures

Figure 1

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Examples of self-repairing cells. Healing…

Figure 1

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Examples of self-repairing cells. Healing of a punctured Xenopus oocyte, where the dark…

Figure 1

Examples of self-repairing cells. Healing of a punctured Xenopus oocyte, where the dark and light halves represent the animal and vegetal poles respectively. Regrowth of damaged axons in neurons. Regeneration of flagella in Chlamydomonas. In each case, regenerated components are highlighted in red. The dots represent the loss of cell content from damage sites.

Figure 2

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The regeneration and reorganization of…

Figure 2

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The regeneration and reorganization of the oral apparatus (green) of Stentor coeruleus .…

Figure 2

The regeneration and reorganization of the oral apparatus (green) of Stentor coeruleus. Blue lines indicate surface pigment stripes, and the red region indicates the oral primordium. At the opposite end from the oral apparatus, Stentor possesses a posterior holdfast, which the cell uses to attach itself to a solid substrate. When an oral apparatus regenerates after removal, it first assembles as an oral primordium, which then migrates to the anterior end and becomes a new oral apparatus.

Figure 3

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Wound healing studies in model…

Figure 3

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Wound healing studies in model cells such as Xenopus oocytes and muscle cells…

Figure 3

Wound healing studies in model cells such as Xenopus oocytes and muscle cells found that the process is triggered by the influx of Ca2+ and oxidative species. These species induce the fusion of membranes derived from intracellular vesicles and organelles, as well as the contraction of actomyosin purse string around the wound site.

Figure 4

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Evidence that oral regeneration in…

Figure 4

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Evidence that oral regeneration in Stentor can be triggered by the loss of…

Figure 4

Evidence that oral regeneration in Stentor can be triggered by the loss of a single oral apparatus. One of the strengths of Stentor as a model system is the ability to graft cells and cell fragments together. In the experiment depicted here, two cells are grafted together to form a doublet cell, which has two oral apparatuses. If one OA is then surgically removed, both of the fused cells form oral primordia (red) such that one half of the doublet regenerates and the other reorganizes.